Air pump of Otto Von Guericke

Ratisbona experiment

Very importants, before the steam engine invention, were the spectaculars experiments made by Otto Von Guericke in 1654 at the town of Ratisbona and at Imperial Diet in Magdeburg.
They demonstrates the great (and unexpected) force of atmospheric pressure.
Von Guericke in 1650 invented the air pump with that he could create a very low air pressure.
With this air pump he extract the air under a piston contained into a cylinder with the diameter of 50,8 centimetres. The piston was attached to a cable who was put around a pulley (see the figure).
The piston, pushed by the atmospheric pressure, unrelenting descended altough the effort of twenty men who pulled in the other (opposite) way.
His most renowned is the Magdeburg experiment, please seeMagdeburg.
After to have joined two metallic hemispheres with a leather gasket, by his pump pulled out the air from the sphere interior (trought a valve).
The air weight, not balanced, compressed the two hemispheres one against the other.
Not even 16 horses (eight toward right and eight toward left) could take off the hemispheres.
The two hemispheres came off as just the air leaved enter into them.

Mgdeburgo experiment (click to enlarge)